Put yeast in water to melt it, for about 5 minutes. Beat the eggs and them to yeast mixture along with the egg yolks, oil, sugar, and salt, and then mix in the flour. Knead dough until smooth and elastic.
Coat dough with a small amount of oil and leave it in a covered bowl. Let dough rise until doubled in size for about one hour. Divide dough in half and separate one half into 6 pieces. Roll out into 30 cm (12 in) long strands. Braid dough. Pinch the ends together to close the braid.
Use semolina (or cornmeal) to dust a parchment paper lined baking sheet or pizza stone. Put bread on it. Braid other blob of dough, creating another 6 strands to braid with. Let dough rise again, and let rest while preheating oven.
Preheat oven to 175 C (350F). Create egg wash mixture by beating egg and combine it with water, and salt. Brush both loaves with egg wash. Thinly coat all surfaces. Wait a few minutes, and then brush again. Optional: sprinkle with poppy seeds or sesame seeds.
Cook bread for about 35 minutes. Halfway through baking, rotate the loaves in oven so that the one on the back is brought to the front for even cooking. Bread is done when it sounds hollow when tapped on the base.